A COUPLE who may have witnessed a city centre sex assault are being asked to come forward.

Police say a woman in her 20s was followed down an alleyway in Newcastle and inappropriately touched, before her attacker was disturbed by a passing couple and ran off.

The incident happened in an alleyway to the side of Monument Mall shortly after 3am on Saturday, September 20.

The Asian attacker is described as being in his mid to late 20s, about 5ft 7ins tall, of chubby build and with short dark hair. He was wearing a long-sleeved blue shirt.

Police say a couple who disturbed the suspect when they walked past the alleyway are both described as being white and slim.

The woman was aged 19 or 20 years old, was wearing a black and white dress, and had long blonde hair which was worn down.

Police ask witnesses, especially the couple who walked past the area at the time, to get in touch on 101 ext 69191, or Crimestoppers on 0800-555-111.